Fading brake pedal

I have a 1995 ford f-350 diesel 2 wheel drive dually , and when i push on the brake pedal the pedal will slowly go to the floor I have replaced the master cylinder, pads and rear shoes including all the hardware front and rear, Ihave checked the vaccume at the booster and have plenty, I also replaced the check valve that goes into the booster, collectivly I have ran 2-3 gallons of brake fluid the system and no air in the system, afterall that Istill have the same problem that I started with. I pull a trailer alot between april and october and as of now I can barely stop the truck letalone the trailer and truck. any help would be appreciated

pedal is stiff when the brakes are first applied then pedal will start going to the floor. no fluid leaks and the pads adjusted uppedal is stiff when the brakes are first applied then pedal will start going to the floor. no fluid leaks and the pads adjusted up

the truck has a proportioning valve that threads in the rear port of the master cylinder and a rear anti lock brake valve on the frame 1 foot under the master cylinder. There is also a rear ABS sensor (R.A.B.S.) in the center and on top of the rear end housing the truck has a proportioning valve that threads in the rear port of the master cylinder and a rear anti lock brake valve on the frame 1 foot under the master cylinder. There is also a rear ABS sensor (R.A.B.S.) in the center and on top of the rear end housing

Make sure that the rear shoes are adjusted up. I take it that there are no leaks ? the next step is to take a vise grip and pinch off the rear brake hose at the diff see is this makes the pedal hard if not try it on the front one wheel at a time .Make sure that the rear shoes are adjusted up. I take it that there are no leaks ? the next step is to take a vise grip and pinch off the rear brake hose at the diff see is this makes the pedal hard if not try it on the front one wheel at a time .

Perfect well at this point i would say that tha abs valve is bypassing fluid. If you can un hook the line that comes into the abs valve and plug it and try and bleed the system where you cap the line going into the abs valve. If you get a good pedal after pluging the line going into the abs valve this tells me that the abs valve is bypassing fluid give it a try i have ran into this a few time and the abs valve has been bad. Also can you rate this sluton also i do hits on my own free time thanks good luck

I've gone threw several master cylinders and the pedal still goes to the floor even after all new pads shoes rotars and drums but the master cylinder doesn't lose break fluid plz help i can't figure this outI've gone threw several master cylinders and the pedal still goes to the floor even after all new pads shoes rotars and drums but the master cylinder doesn't lose break fluid plz help i can't figure this out

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I have the same problem,, put all new brake components on truck, needed it anyway,, found out that the booster is not designed for a diesel application,, ford made a model change for the diesel,, number from ford is F 5 T Z - 2005 CA a zero loss booster,, have ordered on will put on when arrives, $240. good luck,,

You need to crawl under the truck and inspect each brake line for leaks. You also need to check wheel cylinders and calipers. The chances are pretty good that you will find a small leak in a line or a wheel cylinder leaking, pay close attention to the rear of the truck because that is normally where these problems occur. Hope this helps.

you must have a leak in your brakes! check your brake fluid! They may work for now but after all your brake fluid is pushed out they wont work. You better take a look underneath and get someone to press on the brakes to see where it is leaking out. You can keep toping up the brake fluid and that might get you by for a while.

Adjust your rear brake shoes. Then rebleed the system. Start at the master cylinder Bleed master first then the wheel furthest away from the master (right rear then left rear then right front then left front. Do that and your pedal should be good.